The geology of the map below represents geological mapping projects in the Ouachitas and Arkansas River Valley under the COGEO mapping program and in the West Gulf Coastal Plain under the STATEMAP program. You can zoom to a chosen county or quadrangle using the drop-down menus located above the map, and you can adjust the opacity of the surface geology layer using the opacity slider located at the top left corner of the map. For best printing results use either the Mozilla Firefox or Google Chrome web browsers. Click here for full-screen version.